1. Field of the Invention
This invention relates generally to web processing machines, e.g., paper machines and the like, and is concerned in particular with an improved apparatus for doctoring the rolls of such machines.
2. Description of the Prior Art
In known doctoring arrangements of the type disclosed for example in U.S. Pat. No. 5,279,710 (Aikawa); U.S. Pat. No. 4,906,335 (Goodnow et al.) and U.S. Pat. No. 4,665,859 (Dunlap et al.), the doctor blades are carried by holders that are rotatable about pivot rods and the like. Under certain operating conditions, these holders have a tendency to vibrate or chatter due to the clearances that must necessarily be introduced between the relatively rotatable components.
In other known doctoring arrangements of the type disclosed for example in U.S. Pat. No. 6,328,853 (Goodnow et al.), the doctor blades are carried on flexible top plates that are fixed to and extend in cantilever fashion from base components of the holders. Such arrangements beneficially minimize the clearances that are the source of vibration and chattering problems. However, this advantage is partially offset by attendant compromises in blade conformability and uniformity of blade loading across the width of the surface being doctored, and a diminished ability to accommodate cross machine thermal expansion and contraction of the top plate.
An objective of the present invention is to provide an improved doctoring apparatus that eliminates the clearances that are the source of vibration and chattering problems, and that does so in a manner that does enhances blade conformability and uniformity of blade loading, while also accommodating relatively free cross machine thermal expansion and contraction of the blade carrying top plate.
These and other features and objectives of the present invention will now be described in greater detail with reference to the accompanying drawings, wherein: